Printed circuit board connector



Feb. 8, 1966 E. v. PAHOLEK ETAL 3,234,499

PRINTED CIRCUIT BOARD CONNECTOR Original Filed July 31, 1962 2Sheets-Sheet l E. u PAHOL EK /v. WASSERMAN ATTORNEY Feb. 8, 1966 E. v.PAHOLEK ETAL 3,234,499

PRINTED CIRCUIT BOARD CONNECTOR Original Filed July 31. 1962 2Sheets-Sheet 2 United States Patent 3,234,499 PRINTED CIRCUIT BOARDCONNECTOR Edward V. Paholek, Brooklyn, and Norman Wasserman, Jericho, N.Y., assignors to Bell Telephone Laboratories, gg lcorporated, New York,N.Y., a corporation of New ork Continuation of application Ser. No.213,642, July 31, 1962, now Patent No. 3,172,719, dated Mar. 9, 1965.This application Aug. 5, 1964, Ser. No. 387,598

6 Claims. (Cl. 339176) This invention is a continuation of ourapplication Serial No. 213,642, filed on July 31, 1962, that issued asUS. Patent 3,172,719 on March 9, 1965 and relates to electrical devicesfor making connections with printed circuit boards, and morespecifically to electrical devices having terminals that arepre-tensioned in and of themselves.

When making electrical connections between terminals in a connector andtheir mating structure, sufiicient contact force must be supplied to theterminal to insure electrical continuity. Since the majority ofconnectors employ terminals with a spring contact, the contact force isproportional to the deflection of the spring contact. Suiilcient contactforce necessitates either a large deflection of the spring contact orpre-tensioning of the spring contact, the latter being most desirablebut old in the art.

Most connectors comprise an insulating block, having electricalterminals contained within the block in an appropriate geometricpattern. The terminals include a. contact member, the latter mostgenerally being pretensioned against a rib or other suitable restrainingmeans that is part of the connector block. The pre-tensioning isobtained when the terminal is inserted in the connector block. Thecontact member is biased by the rib or restraining means of theconnector block in such manner as to pre-tension the contact member in adesired direction. The terminal in its free position, that is, when itis not inserted in the connector block, is not pre-tensioned because ofthe lack of the interaction between the terminal contact member and therib or restraining means of the connector block. Back up springs, camsand the like are other devices incorporated in other electricalconnectors to obtain adequate pre-tensioning of the terminal contactmember.

The pre-tensioning obtained in the above-mentioned devices is derived bythe interaction of the contact member of the terminal working inconjunction with structures other than that of the terminal. Since theamount of pre-tensioning of the terminal contact member is critical insome applications, it is desirable to be able to measure the amount ofpre-tensioning of the terminals.

Because the above-described terminals derive this pretensioning from theinteraction of the terminal contact member with an appropriate structureof a connector block, the amount of pre-tensioning can not be measuredwithout inserting the terminals in a connector block, special measuringjig or fixture. If an adjustment as to the amount of pre-tensioning isnecessary, the terminal must be extracted from the connector block, jigor fixture, adjusted, and then reinserted back into the block jig orfixture for further measurement and verification. In some instances, theinsulating block may vary in critical dimensions and terminals whichhave been measured and adjusted for the proper amount of pre-tensioningin a special jig or fixture may change in the amount of pretensioningwhen placed in an insulating block. Also, terminals dependent onpre-tensioning derived from the interaction of the terminal contactmember with structure other than its own, are subject to variances incritical dimensions of the structure with which it interacts and theamount of pre-tensioning of a multiplicity of terminals may vary withevery terminal in the insulating block.

An object of the invention is to provide a printed circuit boardconnector wherein the pre-tensioning of the terminal contact members canbe measured and adjusted before the terminals are inserted in theconnector block.

A feature of the invention resides in an electrical conector wherein theterminals of the connector are pretensioned in and of themselves.

A preferred embodiment of the invention comprises an insulating blockhaving a plurality of self pre-tensioned terminals. The terminals areformed out of resilient sheets of electrically conducting material whichare bent back upon themselves near a center portion to form two arms.The second arm is bifurcated from adjacent the first arm to the end ofthe second arm, thereby forming two contact members. Bifurcation of thesecond arm is deemed essential to insure electrical contact between theboard and the connect-or. If dirt or some other foreign insulatingmaterial should by chance prevent electrical continuity between onecontact member and the electrical circuit on the printed circuit board,the other contact member provides an alternate electrical path, therebyinsuring electrical contact between the printed circuit board and theconnector terminal. To further insure electrical contact, each contactmember includes a precious metal contact portion.

On the end of the first arm of the terminal are located two lugs and anembossed portion. The embossed portion cooperates wit-h the insulationblock to properly hold the terminals within the block in predeterminedpositions. Those familiar with the connector art will recognize that thefunction of the embossed portion is to secure the terminal in theconnector block. Other equivalent deforming means such as tabbing andpunching are within the scope of this disclosure. The two lugs areformed to cooperate with the ends of the two contact members. The lugsrestrict the motion of the two members in a direction away from thefirst arm, thereby creating a pre tensioning of the contact members.

The insulation block of the connector has an elongated rectangularcavity in its front surface to receive a printed circuit board. Theterminals are located along the elongated side walls of the block, eachhaving an extended element that protrudes through the rear surface ofthe block to communicate with an electrical conductor. Each terminal isseparated from the next terminal by a rib or protrusion from the sidewall.

The invention will be more clearly understood from the followingdetailed description, when read in conjunction with the drawing, inwhich:

FIG. 1 is an isometric view of the terminal;

FiG. 2 is a sectioned isometric View of a connector showing theterminals and printed circuit board;

FIG. 3 is a section view of FIG. 2 taken through an electrical terminal;and

FIG. 4 is a section view of FIG. 2 taken through a terminal separatingrib. Q

According to the invention, as depicted by the various figures, theconnector comprises an insulating block 10, and a multiplicity ofelectrical terminals 12.

As shown in FIG. 1, the electrical terminals 12 are formed from a fiatsheet of resilient electrically conducting material bent back uponitself to form two arms 13 and 14. The second arm 14 is bifurcated fromnear the arm 13 to the end of arm 14, thereby defining two contactmembers 14A and 1413. The contact members 14A and 14B further includeprecious metal contact portions 15.

The end of the arm 13 is bent at an angle of degrees to itself towardcontact members 14A and 14B. Near the end of the arm 13 are two lugs 16,an embossed portion 17, and an extended element 18. The free ends 19 and20 of the members 14A and 14B are also bent back toward arm 13 so thatthe lugs 16 operatively contact the free ends 19 and 20, restrictingtheir movement in a direction away from arm 13. The restricting of theends 19 and 20 by the lugs 16 pre-tensions the contact members 14A and14B. The terminal is therefore pre-tensioned against itself and theamount of pretensioning can be measured and adjusted while the terminal12 is outside of the connector block 10.

The pre-tensioning is determined during the manufacturing process byfixing the relative positions of the lugs 16 with respect to the ends 19and 20 of the contact members 14A and 14B. If properly made, a terminal12 will not require an. adjustment of the pre-tensioning but it isobvious that if such adjustment is required, bending of the lugs 16either up or down will increase or decrease the amount of pre-tensioningas desired. This process of adjustment can becarried out before theterminal 12 is inserted into a connector block 10. Subseguent insertionof the terminal 12 into the insulating block 10 does not affect theamount of pre-tensioning because the pre-tensioning is in no way afunction of the dimensions of the connector blockltl nor any otherstructure other than its own.

Theconnector block 10 includes a front surface 21 and a rear surface 22.In the'front surface 21 is located an elongated rectangular opening,leadinginto an interior cavity 24. The interior cavity 24 has a floorsurface 23 with rectangular holes,25 that communicate through the floorsurface 23 to the rear surface 22. Along at least one side wall islocated a plurality of terminals 12 separated on the inside of the sidewall by a series of ribs or projections 26. i

The assembly of the connector can best be discussed with reference toFIGS. 3 and 4. The terminals 12', after having been adjusted for theproper amount of pre-tensioning, are inserted into the connector block19. The terminals 1 2 fit between the separating projections 26 so thateach terminal 12 is separated by a rib 26 from its neighbor. Theextended element 18 of the terminals 12 protrude through the rectangularholes 25 in the floor surface 23 to communicate-with incoming electricalconductors by the various known means of soldering, wrapping, crimpingand theother like means. The length and configuration of the extendedelement 18 are determined by the method chosen for making the connectionto the incoming conductors; terminals 12 interfere with the sides of theholes 25 to secure the terminals 12 in the block 10 and to locate themThe embossed portions '17 of the It is obvious that the invention is notlimited to the specific structure illustrated and that it may beemployed by those skilled in the art in ways too numerous to mention.Such use is within the scope of the appended claims.

What is claimed is:

1. An electrical connector for receiving a printed circuit board havinga plurality of spaced circuit paths extending to one edge of said board,comprising the combination of an insulating block and a plurality ofpretensioned terminals; said block having an elongated slot extendinginto a front face of said block for receiving said board, said blockincluding a plurality of ribs extending into said slot to formcompartments in alignment with said paths, said block having openingsextending from said compartments through a rear face of said block, saidcompartments each including at least one of said terminals, each of thelatter comprising a strip of resilient metal bent back upon itself in aportion to format U-shape having two arms, said arms being spaced apartfor their entire length, said arms having free ends distant from saidportion, said first arm having retaining 7 means and pre-tensioningmeans located adjacent its free in a predetermined position againstappropriate reference surfaces. It is to be noted in FIGS. 3 and 4 thatthe precious metal. contact portions 15 with their respective contactmembers, extend beyond the'separating projections 26 to effectelectrical connection with an inserted printed circuit board 28.

The operation of the connector can best be illustrated with referenceto-FIG. 2. The printed circuit board 28 has a plurality of printedcircuit leadsSfl. The dimensions of the terminals 12 and the printedcircuit leads 30 are, suchthat both contact members 14A and 14B of aterminal 12come in contact with a single printed circuit lead 30.

FIG. 2 shows-a printed circuit board 28 inserted in a connector. Itislevident that if dirt or some other foreign insulating substance wasaccidentaly introduced between contact member 14A and its associatedprinted circuit lead 30, that contactmember 14B of thesame terminal 12would provide an alternate electrical path to the same printed circuitlead 30. High reliability is thereby obtained by the dual contact memberstructure.

As mentioned previously, the pre-tensioning of the terminal 12 isaccomplished during manufacturing, and adjustment, if necessary, is donebefore the'terrninal 12 is inserted in the block 10. Insertion of theterminal 12 must he executed without altering or destroying the preten ini g f t e conta t members14A andzletfi end and adapted to butt upagainst the interior side walls of said slot between said ribs, saidretaining means adapted to interfit with said' openings and retain saidterminal in said block, and said pre-tensioning means operativelycooperating with the free end of said second arm to restrain and biassaid second arm in a direction toward said first arm therebypre-tensioning said second arm, said second arm including electricalcontact portions.

2. A connector for a printed circuit board comprising the combination ofaninsulating block and a plurality of self pre-tensioned terminals, saidblock'having front and rear surfaces joined by side walls and anelongated cavity in said front surface to receive said board, said blockhaving ribs projecting from the interior of said cavity side walls thatrun in a direction perpendicular to said front and rear surfaces anddivide said side walls into compartments, each of said compartmentsincluding a mounting opening in said rear surface, each of saidcompartmentsfurther including at least one terminal, the lattercomprising a flat sheet of resilient electrically conducting metal bentback upon itself in a portion to form a U-shape having two arms, saidarms being spaced apart for their entire length, said arms having freeends distant from said portion, said first arm having retaining meansand pre-tensioning means located adjacent its free end and adapted tobutt up against said interior side walls between said ribs, saidretaining means adapted to interfit with said mounting opening andretain said terminal in said block, said pre-tensioning meansoperatively cooperating with the free end of said second arm to restrainand bias said second arm in a direction toward said first armthereby-pre-tensioning said second arm, said secondarmincludingelectrical contact portions,

3. A connector comprising a plurality of self pretensioned terminals incombination with an insulating block, said terminals comprising a fiatsheet of resilient electrically conducting material bent back uponitself in a portion to form a U-shape having two arms, said arms beingspaced apart for their entire length, each of the latter having a freeend distant from said portion, the free end of said first arm being bentat a degree angle to .itself toward said second arm, said last mentionedend including retaining means and restraining lugs, said retaining meansbeing adapted to retain said terminals;

'in said block, said second arm being bifurcated from adjacent saidfirst arm to the end of said second arm: to form two contact elements,said lugs restraining mo-- tion of said elements in a direction awayfrom said first arm'but permitting motion of said elements toward saidfirst arm, therebypre-tensioning said elements, said in-.

sulating block having front and rear surfaces joined-byside walls and anelongated rectangular cavity in said front surface to receive a printedcircuit board, said insulating block further having projections from theinterior side Walls of said cavity, said .projections running in adirection perpendicular to said front and rear surfaces dividing saidside walls into terminal receiving openings, each of said openingsincluding at least one of said terminals.

4. An electrical terminal comprising a flat sheet of resilientelectrically conducting material bent back upon itself in a portion toform a U-shape having two arms, said arms being spaced apart for theirentire length, the latter having free ends distant from said portion,the first arm having retaining means and pre-tensioning means locatedadjacent its free end, said retaining means being adapted to retain saidterminal in an insulating block, said pre-tensioning means operativelycooperating with the free end of the second arm to restrain and biassaid second arm in a direction toward said first arm, therebypre-tensioning said second arm, said second arm including electricalcontact portions.

5. An electrical terminal according to claim 4 wherein saidpre-tensioning means comprises two lugs and said second arm isbifurcated from adjacent said first arm to the end of said second armdefining two contacts, said lugs operatively cooperating with the endsof said contacts to restrain and bias said ends in a direction towardsaid first arm.

6. An electrical terminal comprising a flat sheet of resilientelectrically conducting material bent back upon itself in a portion toform a U-shape having two spaced apart arms, each of the latter having afree end distant from said portion, the free end of said first arm beingbent at a 90 degree angle to itself toward said second arm, said lastmentioned end including retaining means and UNITED STATES PATENTS1,531,816 3/1925 Russell 339-262 3,015,083 12/1961 Juris 3391763,040,291 6/1962 Schweitzer et al 339176 3,076,171 1/1963 Hopkins 3392583,131,017 4/ 1964 Mittler 339--176 FOREIGN PATENTS 882,698 11/1961 GreatBritain.

References Cited by the Applicant UNITED STATES PATENTS 2,309,311 1/1943Grohsgal. 2,539,230 1/1951 Craig. 2,682,038 6/ 1954 Johnson. 2,975,3953/1961 Sitz. 3,032,741 5/1962 Fitz Gerald. 3,040,291 6/ 1962 Schweitzeret a1.

IGSEPH D. SEERS, Primary Examiner.

W. DONALD MILLER, ALBERT H. KAMPE,

Examiners.

4. AN ELECTRICAL TERMINAL COMPRISING A FLAT SHEET OF RESILIENTELECTRICALLY CONDUCTING MATERIAL BENT BACK UPON ITSELF IN A PORTION TOFORM A U-SHAPE HAVING TWO ARMS, SAID ARMS BEING SPACED APART FOR THEIRENTIRE LENGTH, THE LATTER HAVING FREE ENDS DISTANT FROM SAID PORTION,THE FIRST ARM HAVING RETAINING MEANS AND PRE-TENSIONING MEANS LOCATEDADJACENT ITS FREE END, SAID RETAINING MEANS BEING ADAPTED TO RETAIN SAIDTERMINAL IN AN INSULATING BLOCK, SAID PRE-TENSIONING MEANS OPERATIVELYCOOPERATING WITH THE FREE END OF THE SECOND ARM TO RESTRAIN AND BIASSAID SECOND ARM IN A DIRECTION TOWARD SAID FIRST ARM, THEREBYPRE-TENSIONING SAID SECOND ARM, SAID SECOND ARM INCLUDING ELECTRICALCONTACT PORTIONS.